“What you want to do is when you wake up the next morning, feel good that you took the best player in the draft,” Casserly said on the NFL Network’s “Road to the Draft” show last month. “The best talent in the draft is Jadeveon Clowney. Guy makes rare plays against the run, rare plays against the pass. Maybe the most talented defensive end I’ve ever scouted.”

But Casserly says Clowney at No. 1 is not a slam dunk.

“There are a lot of plays where he doesn’t come off blocks as well as I would like,” Casserly said, “and he has to develop a counter move on the pass rush. This is not a no-brainer.”

As a sophomore in 2012, Clowney had 13 sacks and 23.5 tackles for loss. As a junior in 2013, he had just three sacks and 11.5 tackles for loss.

“Even though his production this year wasn’t near what it was last year, he had two or three guys waiting on him just about every play,” said South Carolina coach Steve Spurrier in an NFL Network interview. “His run defense was very good, though, and he chased down a bunch of guys and made tackles.”

How did Spurrier assess Clowney’s work ethic in 2013? “He was OK. ... You know, every player is a little different. His work habits are pretty good.”

Clowney on his drop in sack production: “This year, a lot of things didn’t go as planned. ... Teams played me different, played our team different. When we watched them on film, they took three or four seconds to throw the ball. You watch them after our game, and they took like two seconds. So they changed the game plan because of our defensive line.”

Kiper says Clowney showed good effort.

“I didn’t see the lack of hustle, I didn’t see the lack of effort,” he said. “I saw a guy who played hard 90 percent of the time. To me he is the No. 1 pick, whether he goes to the Houston Texans or somebody else.”

The No. 2 defensive lineman in the draft is the clear-cut choice as the top defensive tackle: Pittsburgh’s Aaron Donald. He’s likely to be taken in the top dozen or so.

Donald, 6-1 and 285, is a tad short but makes up for it with quickness. In 2013, he had 11 sacks, 28.5 tackles for loss, 16 hurries and four forced fumbles.

He starred at the Senior Bowl. He’s a prototypical 3-technique defensive tackle in the mold of Cincinnati All-Pro Geno Atkins.

The best nose tackle is Notre Dame’s Louis Nix, a 331-pounder. The top 3-4 defensive end prospect arguably is Notre Dame’s Stephen Tuitt. He’s a late first-round pick. So is Minnesota’s Ra’Shede Hageman, a bruising defensive tackle who’s scheme versatile.

Florida State’s Timmy Jernigan could go in the second half of the first round, but there’s debate over whether he fits at nose tackle, the 3-technique (penetrator) position or neither. Edge rushers who figure to be taken by the first half of the second round include Auburn’s Dee Ford, Missouri’s Kony Ealy and maybe Oregon State’s Scott Crichton.